Preparation And Photocatalytic Properties Of GC 3 N 4 Based Composites

In recent years, the problems of environment and energy gradually affect the life and production of our human beings. In order to solve energy problems, energies such as wind energy, hydroenergy, solar energy are attempted to be used. Among them, solar energy has attracted more interests from researchers due to the endless supplement. In case of environment problem, many technologies are developed. Nowadays, photo-degradation has attracted much attention from governments, research groups, enterprises. Semiconductor photo-catalyst could absorb light, which may convert to chemical energy reserved in productions. Graphite like carbon nitrogen(g-C3N4) could absorb visible light due to the suitable energy band. These energy could be converted to chemical energy reserved in carriers(both for electron and hole). Therefor, g-C3N4 has been paid interests for many researchers. However, g-C3N4 made by the traditional method may have its shortcomings: high energy band, high recombination rate between electron and hole, low surface areas. These shortcomings may lead to low light absorption, low quantum efficiency, unsatisfied catalytic carriers. Therefore g-C3N4 needs to be modified.To increase the catalytic properties of g-C3N4, three methods are developed. By doping elements, integrating with other compositions, and increasing surface areas, the photo-catalytic property could be increased. For a decrease of energy band may lead to a high absorption of light, and the integrating with other compositions leads to an low recombination rate between electron and hole. A high surface areas could provide enough space to react. Melamine acidified by sulfuric acid could be thermal-polymerized to synthesis porous g-C3N4, which may provide an efficient way to obtain g-C3N4 with high surface areas. The as prepared g-C3N4 could be integrated with Ti O2, Ag Cl and Ag, which may form hetero-structure leading to a high rate for catalytic property. Besides, the usage of SBA-15 in the process of pyrolysis could produce SBA-15/g-C3N4, which has a high surface areas. g-C3N4 was dispersed along the surface of SBA-15 via an in-situ method. Once again, the as prepared SBA-15/g-C3N4 could be modified by integrating with Ag, Ag Cl and Ti O2. The experience of photo-degradation shows an increased catalytic property, which is due to the hetero-structure formed in the integrating processing.The main contents are as follows:1. Melamine was acidified by sulfuric acid, then, porous g-C3N4 could be prepared by a one step method of thermal-polymerization. The as prepared porous g-C3N4 was characterized by XRD, BET surface areas, DRS, PL to obtain the structure, morphology, light absorption, and fluorescent properties. In the end, the catalytic property was characterized by photo-degradation of phenol and methyl orange.2. The as prepared g-C3N4 was modified by Ag, Ti O2, and Ag/Ag Cl/Ti O2 respectively. A serious of g-C3N4 compounds were then prepared. The obtained samples were characterized by XRD, TEM, DRS, and PL. An increased catalytic property was obtained in g-C3N4 compounds when compared with g-C3N4, which indicated that the heterostructure could benefit for the catalytic property of g-C3N4. Besides, sample of g-C3N4/Ag/Ag Cl/Ti O2 had an even more high rate of photocatalytic property, which was due to the synergy and the high transmission rate of charge carrier.3. SBA-15 and melamine were mixed together, then, SBA-15/g-C3N4 with high surface areas was obtained by one step of pyrolytic method. The SBA-15/g-C3N4 was once again modified by Ag/Ag Cl, Ti O2, and Ag/Ag Cl/Ti O2 respectively. The obtained samples of SBA-15/g-C3N4/M were characterized by XRD, TEM, DRS, and PL to acquire the crystalline structure, hetero-structure, light absorption, and fluorescent properties. The catalytic properties were also evaluated, and the results showed that SBA-15/g-C3N4/M had even more high catalytic properties than SBA-15/g-C3N4. The increased catalytic properties were due to the hetero-structure, of which leaded to an stronger visible light absorption and more efficient inhibition of recombination between electron and hole. The above results indicated that SBA-15 could be used to increased the catalytic property of g-C3N4, even more, SBA-15/g-C3N4 could also be modified by integrating with Ag/Ag Cl, Ti O2, and Ag /Ag Cl/ Ti O2.